Blade lock



April 8 970 3.v P. LE BLANC 3,508,844

BLADE LOCK Filed July 25, 1968 Z 1 JF|I|\\ x, 1! H V 47 16 xx & mmmn i6 "v v \r v M .Z/VI/E/VTaQ 667,965 1 1 e31 A7/V6' United States Patent 3,508,844 BLADE LOCK George P. Le Blanc, East Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed July 25, 1968, Ser. No. 747,524 Int. Cl. FOld 5/32 US. Cl. 416221 6 Claims ABSTRACT OF THE DISCLOSURE A turbomachine having a rotor assembly construction wherein a blade lock construction is employed between the blade root and the rotor disk to prevent any axial movement of the blade root in the rotor disk.

BACKGROUND OF THE INVENTION This invention relates to a rotor assembly for use in a turbomachine and more particularly to a blade lock therein.

It is clear that in a turbomachine some arrangement must be provided to hold or lock the blades in place in the rotor assembly. Probably the most common method of retaining blades in a turbine which the prior art employs is the use of a pin which extends in a generally radial direction through the wheel into the base of the blades. Probably the most common method of retaining blades in a compressor which the prior art employs is the use of keys or padlocks which lie beneath the root of the blades at the bottom of the blade slots and are fixed to the wheel and blade.

While these and other similar locking devices provide adequate blade retention, they have a number of inherent disadvantages. For example, the pin-type locking device weakens the wheel at a point of very high stress with the result that the entire wheel must be made heavier than would otherwise be necessary, and this type of locking device also tends to reduce the tangential blade tip wobble when the assembly is cold. The key or blade lock retention is normally weak in the axial direction with the result that the blades may walk out of the wheel slots.

SUMMARY OF THE INVENTION It is a primary object of this invention to provide a rotor assembly with a stronger and improved blade lock which is readily applied and removed while not weakening the rotor disk assembly.

In a preferred embodiment of the present invention, the rotor assembly which employs the blade lock construction hereinafter described, contains a blade which when inserted in the rotor disk slot is prevented from moving axially in one direction by stop means on the blade root, which cooperate with or abut against the rotor disk face. After insertion of the blade in the blade receiving slots within the rotor disk, the one end of the blade extends axially beyond the rotor disk, this end being the root portion remote from the root end having the stop means. The blade root at this end, contains a circumferential slot which extends transversely from one side of the blade root to the other side. This slot is positioned in the blade root portion such that when the blade is inserted into the disk slot the circumferential slot is past the disk face and lies in a plane which is generally parallel to the plane of the disk.

Inserted within this slot is a plate lock, this plate lock once inserted within the circumferential slot being in abutting relationship with the face of the disk and retaining or preventing an axial movement of the blade. This plate lock includes two outwardly extending legs which straddle 3,508,844 Patented Apr. 28, 1970 or abut the blade root portion on each side of the root and thereby limit or prevent any side movement of the plate lock.

To lock the plate lock to the root portion and thereby prevent any axial movement on the root within the disk, a deformable retaining lock is employed. This retaining lock consists of a normally outwardly extending tab at one end, the end remote therefrom being a generally axially extending tab. When the retaining lock is inserted into the transverse or circumferential slot in the blade root, the outwardly extending portion abuts the blade root face, and the axially extending portion extends beneath the plate lock and past the root portion face containing the stop means. This latter stop means in the embodiment herein illustrated comprises a pair of radially extending tabs with a space therebetween. The deformable retaining lock passes through this space and is deformed upward from its normally axial position to an outwardly extending position and abuts the face of the root portion.

The blade lock construction of the present invention provides a construction which is strong in the direction where failures generally occur. More specifically, before a blade will fall out of a rotor assembly employing the construction described herein, the blade lock must fall in four positions; that is, two at the plate lock and two at the integral blade tabs forming the stop means. Additionally, the construction by employing a deformable retaining lock provides a construction which is readily removable or replaceable.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a fragmentary sectional View of a blade root portion.

FIGURE 2 is a fragmentary side view of a rotor assembly showing the blade root portion assembled to the rotor disk.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGURE 2 for a description of an illustrative embodiment of the invention, a compressor rotor 10 supports a series of radially extending blades 12 mounted in peripheral slots 14 extending from the rear or first face 16 of the rotor to its forward or second face 18 in a direction substantially axial with respect to general disposition of the rotor.

Each blade 12 includes a root section 20 and in the embodiment illustrated in FIGURE 1, root section 20 has a pair of integral inwardly extending flanges 22 and 24, each of these integral flanges abutting against first face 16, thereby effectively preventing axial movement of the blade in one direction. The end of blade root 20 opposite flanges 22 and 24 contains a circumferential slot 26. Circumferential slot 26 extends transversely from side 28 of root portion 20 to side 30 of root section 20 and is positioned within the root section such that it lies in a plane that is generally parallel to the plane of rotor disk 10. Additionally, the slot 26 is positioned within root 20 such that when plate lock 32 is inserted into the circumferential slot 26, the extending portions of plate lock 32 abut against second face 18 of rotor disk 10.

Plate lock 32 includes means for limiting or preventing any side movement of plate lock 32. These means comprise a pair of outwardly extending legs 34 and 36 which straddle the blade root portion 20 and are substantially in abutting relationship with each side of the root portion 20. Locking the plate lock 32 into position and connecting the blade root portion to rotor disk 10 is retaining lock 40. Retaining lock 40 is preferably a sheet metal member which is deformable at one end. As herein illustrated, end 42 is preformed into an outwardly extending tab 44 which abuts against first face 116. Retaining lock 40 includes an axially extending portion 46 which passes through circumferential slot 26 and beneath the plate lock 32 thereby positioning or securing the plate lock 32 within the slot. The end remote from the deformed end is initially an axially extending member which is deformable into an outwardly extending tab 48. Initially, the axially extending tab, prior to being deformed, passes through slot 26 beneath the plate lock 32 and between the space 50 of the integral tabs 22 and 24 of root portion 20. After the retaining lock 40 has been positioned in such a manner, the deformable end is deformed upward and the retaining lock then has two outwardly extending tabs, this being illustrated in FIGURE 2. Any outward or radial movement of plate lock 32 and retaining lock 40 is limited by the height of circumferential slot 26.

I claim:

1. A rotor assembly for a turbomachine comprising a disk having blade receiving slots in the periphery thereof extending generally axially from the first side of the disc, and removable blades including a root portion slideably mounted in the slots, wherein the improvement comprises:

one end of the root portion having stop means which means for securing the lock plate to the blade root,

the stop means, plate lock and securing means cooperating to limit any movement of the blade root when positioned in the blade receiving slots in the disk.

2. A construction as in claim 1 wherein:

the stop means comprise a pair of integral tabs extending radially inward and which abut against the first side of the disk and thereby position the blade axially.

3. A construction as in claim 1 wherein:

the plate lock means for limiting side movement of the plate lock comprises a pair of outwardly extending legs which straddle the blade root portion and are substantially in abutting relationship with each side thereof.

4. A rotor assembly for a turbomachine comprising a disk bearing blade receiving slots in the periphery thereof extending generally axially from one face of the disk to the opposite face of the disk, and removable blades including a root portion slideably mounted in the slots wherein the improvement comprises:

one end of the root portion having stop means abutting against one face of the disk and preventing axial movement of the root in one direction, the end of the blade root opposite the one with the stop means having a slot which extends transversely from one side of the root to the other side, the transverse slot being positioned in the root portion such that it is axially beyond the blade receiving slots and lies in a plane which is generally parallel to the plane of the disk;

a plate lock positioned in the transverse slot, the plate lock being in abutting relationship with the face of the disk and including means positioned on either side of the root portion to limit side movement of the lock plate; and

a retaining lock extending from the face of the root portion containing the transverse slot to the face containing the stop means, the lock passing through the transverse slot and beneath the lock plate thereby locking the lock plate in position and preventing any axial movement of the root portion in the blade receiving slots.

5. A construction as in claim 4 wherein:

the retaining lock is deformable, one end thereof being an outwardly extending tab, the end opposite therefrom being a normally axially extending tab which is deformable to an outwardly extending tab.

6. A construction as in claim 5 wherein:

the height of the transverse slot in the root portion limits the radial movement of the retainer lock and lock plate.

References Cited UNITED STATES PATENTS 2,641,443 6/1953 Comery et al. 2,755,062 7/1956 Hill. 2,994,507 8/ 1961 Keller et al. 3,137,478 6/ 1964 Farrell. 3,216,699 11/1965 Schoenborn.

EVERETTE A. POWELL, JR., Primary Examiner 

